Carbon: Study with Video Lessons, Practice Problems & Examples

Carbon is a fundamental element in organic chemistry, forming the backbone of essential macromolecules: carbohydrates, proteins, nucleic acids, and lipids. Its ability to create four covalent bonds allows for diverse structures, including variations in backbone length, double bond positions, branching, and ring formations. Organic molecules contain covalently linked carbon and hydrogen, while hydrocarbons consist solely of these two elements. Understanding carbon's versatility is crucial for grasping biological processes and molecular interactions.

Carbon

In this video, we're going to begin our lesson on the element carbon. Now, of all the bulk elements, which recall from our previous lesson videos are carbon, hydrogen, nitrogen, oxygen, phosphorus, and sulfur or CHNOPS. If we exclude water then it's actually the element carbon that is the most abundant element in living systems. And so that goes to show how important the element carbon is to living things. Now, carbon is the main component of organic molecules, and really there are 4 classes of organic molecules that we're going to talk about moving forward in our course in separate videos, and those 4 classes of organic molecules are carbohydrates, proteins, nucleic acids, and lipids. And once again, carbon is the main component of these molecules. Now the terms organic molecules are really just referring to any molecule with covalently linked carbon and hydrogen atoms. And so if the molecule contains covalently linked carbon and hydrogen atoms at some point within the molecule, then we refer to it as an organic molecule. Now the term hydrocarbons, on the other hand, as its name implies, are organic molecules themselves that are only made up of carbon and hydrogen atoms, and so they contain no other elements. Again, hydrocarbons shows that they only have hydrogens and carbons, whereas organic molecules that are not hydrocarbons, they can have other types of atoms. So just to get a better feel for this, let's take a look at our example down below, which is asking us to circle the organic molecules in green and then highlight the hydrocarbons in yellow. And so when we take a look at these structures that we have down below, notice that this molecule over here has a carbon covalently bound to a hydrogen, so that makes it an organic molecule. So we'll go ahead and circle this one in green right here. Then notice this one over here has an oxygen bonded to hydrogens, and this is a water molecule. But water molecules are not organic molecules because they don't have covalently linked carbon and hydrogen atoms. So this is not going to be an organic molecule. And notice this over here is CO₂ or carbon dioxide, and once again, CO₂, it does not have covalently linked carbon and hydrogen atoms, so this is not going to be an organic molecule. Now notice that this one over here does have carbon and hydrogen covalently linked together so that makes this an organic molecule and we can circle it in green. And then last but not least over here, notice that this one also has carbon and hydrogen bound, and so that also makes it an organic molecule. We can go ahead and circle it. So now to identify the hydrocarbons, the hydrocarbons are going to be organic molecules that are only made of carbon and hydrogen atoms. So if we take a look at option a over here, notice that this is methane, which is only made up of carbon and hydrogen atoms. So that makes this a hydrocarbon, and so we can go ahead and highlight it in yellow. And really the same goes for option d over here. It is only containing carbon and hydrogen atoms. So once again, that makes this a hydrocarbon as well. But then notice that this last one over here has an oxygen atom over here, and so it is not only made up of carbon and hydrogen atoms if it has an oxygen in it. And so this one is an organic molecule but it is not a hydrocarbon. And so, as we see here, this is the correct answer to this example. And so this here concludes our introduction to carbon and we'll get to talk a little bit more about the element carbon in our next lesson video. So, I'll see you all there.

Organic molecules are defined as chemical compounds that contain:

a) Carbon.

b) Carbon & Oxygen.

c) Carbon & Nitrogen.

d) Carbon & Hydrogen.

• A. Carbon.
• B. Carbon & Oxygen.
• C. Carbon & Nitrogen.
• D. Carbon & Hydrogen.

Carbon is an Excellent Building Block

So the element carbon is actually an excellent building block and so in this video we're going to focus on that idea. Now carbon's ability to form a total of 4 covalent bonds really is what makes it such a flexible atomic building block for building a variety of different types of molecules. And so the carbon backbones of organic molecules such as carbohydrates, proteins, nucleic acids, or lipids can actually vary in 4 different ways that we have listed down below right here. And those are in the length of the carbon backbone, the position of double bonds within the carbon backbone, the branch points of the carbon backbone, and the carbon backbone being in either a linear form or a ring form.

And so if we take a look at our example image down below, we can see the variations of carbon backbones. And so over here in the first image, what we're showing you is how, number 1, which of course corresponds with number 1 up above, is that the length of carbon backbones, are capable of changing. And so notice that this first molecule over here has 2 carbons in its carbon backbone, whereas this molecule over here has 3 carbon atoms in its backbone. And so you'll see different molecules throughout that have different lengths of the carbon backbone.

Now the second one are the positions of double bonds within the carbon backbone. Notice that this molecule over here has a double bond between the first 2 carbons in the carbon backbone, whereas this molecule over here has a double bond between the 2nd and the 3rd carbon atoms in the carbon backbone, and so the position of the double bond can vary.

Now the third characteristic here of carbon backbones are the branch points. And so, of course, you can have a linear carbon backbone that does not have any branch points, but notice this molecule over here actually has a carbon backbone and another backbone that is branching off of it, and so here we have a branched carbon backbone.

Now the 4th and final characteristic here are the ring forms. And so, of course, we've seen examples of the carbon backbone being in a linear form like all of these, but the ones that you see down below show that the carbon backbone can be in a ring form as we see over here and over here, and notice that the ring form can also have double bonds within it as well. And so this here just goes to show how a lot of the molecules that we're going to talk about moving forward, they're going to be built using carbon as the backbone. And carbon is a really useful atomic building block, because it can be built in so many different fashions as we see right here, and that's really the main takeaway here of this video.

And so that concludes our lesson on how carbon is such an excellent building block and we'll be able to see these concepts applied as we move forward throughout our course. So I'll see you all in our next video.

Here’s what students ask on this topic:

What makes carbon such a versatile element in organic chemistry?

Carbon's versatility in organic chemistry stems from its ability to form four covalent bonds. This allows carbon atoms to create a wide variety of structures, including chains, branched molecules, and rings. Additionally, carbon can form single, double, and triple bonds, further increasing the diversity of possible molecules. This flexibility is crucial for the formation of the four major classes of organic molecules: carbohydrates, proteins, nucleic acids, and lipids. These variations in structure enable carbon to serve as the backbone for complex molecules essential for life.

What are the four main classes of organic molecules that contain carbon?

The four main classes of organic molecules that contain carbon are carbohydrates, proteins, nucleic acids, and lipids. Carbohydrates are primarily used for energy storage and structural purposes. Proteins serve a wide range of functions, including catalyzing biochemical reactions and providing structural support. Nucleic acids, such as DNA and RNA, store and transmit genetic information. Lipids are involved in energy storage, cell membrane structure, and signaling. Carbon's ability to form diverse structures makes it a key component in these essential biological molecules.

What is the difference between organic molecules and hydrocarbons?

Organic molecules are compounds that contain covalently linked carbon and hydrogen atoms, but they can also include other elements such as oxygen, nitrogen, sulfur, and phosphorus. Hydrocarbons, on the other hand, are a specific type of organic molecule that consists solely of carbon and hydrogen atoms. While all hydrocarbons are organic molecules, not all organic molecules are hydrocarbons. For example, methane (CH₄) is a hydrocarbon, whereas glucose (C₆H₁₂O₆) is an organic molecule but not a hydrocarbon because it contains oxygen atoms.

How do variations in carbon backbones contribute to molecular diversity?

Variations in carbon backbones contribute to molecular diversity in several ways. First, the length of the carbon backbone can vary, leading to molecules of different sizes. Second, the position of double bonds within the carbon backbone can change, affecting the molecule's properties. Third, carbon backbones can have branch points, creating more complex structures. Finally, carbon backbones can form linear or ring structures, each with unique characteristics. These variations allow for the formation of a wide range of molecules with different functions and properties, essential for the complexity of biological systems.

Why is carbon considered the most abundant element in living systems, excluding water?

Excluding water, carbon is considered the most abundant element in living systems because it is the primary component of organic molecules, which are essential for life. Carbon's ability to form four covalent bonds allows it to create a diverse array of complex molecules, including carbohydrates, proteins, nucleic acids, and lipids. These molecules are crucial for various biological processes, such as energy storage, genetic information transmission, and cellular structure. The versatility and abundance of carbon make it a fundamental element in the chemistry of life.